   (first (validate* partitioner (seq dirs))))
 
 
+;; ## Concrete Partitioners
+
 (defrecord ^{:doc "A vertical partitioner that places all objects in the root directory. In other
                   words, it does not vertically partition the data."}
   NullPartitioner []

  [partitioner dirs]
  (validate partitioner dirs))


(defn vertical-partition
  "Returns the vertical partitions for an object as a list of strings."

           (rest dirs)])                      ; return remaining directories"))


;; ## Testing Hooks

(defn make-partition*
  "Calls the underlying protocol implementation. This can be used as a mocking point to unit test
  implementations of `make-partition` that compose other partitioners."
